A build-up of fluid in the cavities deep within the brain.

Rare

Fewer than 200,000 US cases per year

Treatable by a medical professional

Requires a medical diagnosis

Lab tests or imaging always required

Medium-term: resolves within months

Critical: needs emergency care

The extra fluid puts pressure on the brain and can cause brain damage. It's most common in infants and older adults.

Hydrocephalus is characterized by head enlargement in infants. Adults and older children experience headache, impaired vision, cognitive difficulties, loss of coordination, and incontinence.

People may experience:

Muscular: abnormality walking, instability, problems with coordination, or stiff muscles

Gastrointestinal: nausea or vomiting

Cognitive: memory loss or mental confusion

Also common: blurred vision, bulging soft spot on a baby's head, delayed development, enlargement of head, headache, high pitched cry, irritability, leaking of urine, or sleepiness

Snuffle: So no, people, it's not a virus. Don't assume that it is because it is not. Sorry if I sound rude, but I'm just telling you the truth.